Apparatus and methods for recovering abrasive from an abrasive-laden fluid for use with abrasive jet cutting systems

ABSTRACT

This invention relates to methods and apparatus for recovering abrasive for use with abrasive jet cutting systems. In one embodiment, an apparatus in accordance with the invention includes an abrasive-laden fluid handling device coupled to a catcher tank of an abrasive jet cutting system, a pre-classifier fluidly coupled to the abrasive-laden fluid handling device, a hydro-classifier fluidly coupled to the pre-classifier, a fine-particle separation tank fluidly coupled to a clarified-fluid flow outlet of the hydro-classifier, a wet abrasive receptacle positioned to receive a wet recovered abrasive discharged from the hydro-classifier, a de-watering device engageable with the wet recovered abrasive in wet abrasive receptacle, and a dryer unit. The abrasive-laden fluid handling device may include an abrasive-laden fluid conduit having a first end in fluid communication with the catcher tank and an abrasive-laden fluid outlet. Alternately, the abrasive-laden fluid handling device may include a fluid drive system. In another embodiment, a de-watering device includes a housing having a wet abrasive intake and a de-watered abrasive, and an eductor port situated along an abrasive travel path extending between the wet abrasive intake and the de-watered abrasive outlet, an eductor inlet coupled to the eductor port and coupleable to a source of eduction air, and a transport device. In a further embodiment, an apparatus includes an airflow control valve fluidly coupled to the eductor port and positionable in a first position to draw an entrained airflow from within the housing through the eductor port, and a second position to backflow the eduction air through the eductor port into the housing.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. Patent applicationSer. No. 09/069,223, filed Apr. 28, 1998, now U.S. Pat. No. 6,299,510now pending and incorporated herein by reference, which application andinvention are commonly assigned to the Assignee of the presentapplication

TECHNICAL FIELD

This invention relates to apparatus and methods for recovering abrasivefrom an abrasive-laden fluid for use with abrasive jet cutting systems.

BACKGROUND OF THE INVENTION

Abrasive-jet cutting systems are used for cutting a wide variety ofmaterials and for the production of a wide variety of products. In atypical abrasive-jet cutting system, abrasive particles are mixed withan ultra-high pressure fluid (e.g. water), and the resulting ultra-highpressure abrasive fluid is flowed through a cutting nozzle which directsan abrasive cutting jet onto a workpiece. The cutting nozzle may then becontrollably moved across the workpiece to cut the workpiece into thedesired shape. After the ultra-high pressure abrasive jet passes throughthe workpiece, the energy of the abrasive jet is dissipated and theabrasive fluid is collected in a catcher tank for disposal. Abrasive-jetcutting systems of this type are shown and described, for example, inU.S. Pat. No. 5,643,058 issued to Erichsen et al and assigned to FlowInternational Corp. of Kent, Wash., which patent is incorporated hereinby reference, corresponding to Flow's Bengal 4×4 and Paser 3abrasive-jet cutting systems.

One abrasive material commonly used in abrasive-jet cutting systems isgarnet. Garnet is well-known for its hardness, resiliency, and overallperformance in abrasive-jet cutting systems for a wide variety ofworkpiece materials. The cost of garnet, however, is not insubstantial.In existing abrasive-jet cutting systems the consumable garnet particlesrepresent 60 to 75 percent of the operating costs of the system.Research into the recovery and recycling of garnet particles indicates,however, that between 40 and 60 percent of the garnet particles aretypically large enough to be recovered and recycled after initial usedepending upon the material properties of the workpiece being cut. Thisfact makes abrasive recycling commercially viable.

Currently, abrasive recovery apparatus for use with abrasive-jet cuttingsystems may be divided into two broad categories. In a first category,the abrasive-laden fluid contained within the jet catcher of theabrasive jet cutting system is simply removed to a heater and subjectedto heat to evaporate the fluid, leaving a mixture of abrasive particlesand cuttings (or “fines”) from the workpiece. This mixture of abrasiveparticles and cuttings is then sifted, such as through a system ofsuccessive screens, to remove the desirable abrasive particles from theundesirable cuttings and unusable particles.

In a second category, the abrasive-laden fluid is removed from the jetcatcher and is separated by a wet separation process known as“classification” into a low-concentration abrasive flow and a wetrecovered abrasive. The wet recovered abrasive is then heated toevaporate the fluid, leaving a mixture of dry recovered abrasive andcuttings for segregation. The low-concentration abrasive flow may simplybe disposed of, or may be transported to a fine-separation tank to allowthe fine particulates to settle and be recovered. In this secondcategory of abrasive recovery systems, energy savings may be achievedbecause the low-concentration abrasive flow is not heated, withcorrespondingly lower operational costs. An abrasive recycling system ofthis type is shown and described, for example, in DE 19645142 issued toHering et al and assigned to Intrec Ges Innovative Technologien MbH ofBerlin, Germany, which patent is incorporated herein by reference.

FIG. 1 is a schematic view of an existing abrasive recovery apparatus 10of the type that uses classification. First, an abrasive-laden fluid 22is pumped through the cutting head 12 to form an abrasive jet 14. Theabrasive jet 14 is passed through a workpiece and collected in a catchertank 16. A pump 18 draws the abrasive-laden fluid 22 from the catchertank 16 and pumps it through a bypass 20 to a hydro-classifier 34.

The abrasive-laden fluid 22 enters into an upper portion 36 of ahydro-classifier 34. A clear-fluid pump 38 draws a clarified fluid 30from a reserve tank 32 and pumps it into a lower portion 40 of thehydro-classifier 34. The abrasive-laden fluid 22 passes downwardlythrough a middle portion 42 of the hydro-classifier 34, while theclarified fluid 30 passes upwardly through the middle portion 42. Theresulting mixing in the middle portion 42 of the hydro-classifier 34causes the abrasive-laden fluid 22 to separate into a recovered abrasive44 and a fine-particle flow 46. The recovered abrasive 44 collects inthe bottom portion 40 of the hydro-classifier 34. The fine-particle flow46 is routed to a clearing tank 26 for separation as described below.

The recovered abrasive 44 exits from the hydro-classifier 34 to a wetabrasive storage receptacle 47. If the wet abrasive storage receptacle47 becomes filled to capacity, the bypass 20 directs the abrasive-ladenfluid 22 directly to the clearing tank 26. An auger 48 transports therecovery abrasive 44 from the wet abrasive storage receptacle 47 to adryer 50. In the dryer 50, the recovered abrasive 44 is heated to removeany remaining moisture, and is shaken and sifted through screens toseparate the recovered abrasive 44 from any non-reusable particulates.The recovered abrasive 44 is then deposited into a collection tank 52for reuse in the abrasive jet cutting system.

The fine-particle flow 46 is shunted to the clearing tank 26 where theparticles are permitted to settle to the bottom. A sediment 27 whichcollects at the bottom of the clearing tank 26 includes cuttings fromthe workpiece as well as fine, non-reusable abrasive particulates. Thesediment 27 is collected in a receptacle 28 for disposal or subsequentprocessing. Clarified fluid 30 exits from the settling tank 26 and iscollected in the reserve tank 31. From the reserve tank 31, theclarified fluid 30 may be pumped by a filter pump 32 through a filter 33and into a waste disposal system (not shown). Alternately, the clarifiedfluid 30 may be pumped by a return pump 35 from the reserve tank 31 backto the catcher tank 16 as necessary.

Although desirable results may be achieved using the abrasive recoveryapparatus 10, certain characteristics may be improved. For example, theenergy costs associated with the dryer 50 remain high and the throughputof the dryer 50 is low. Furthermore, the hydro-classifier 34 istypically extremely large. These characteristics tend to make theabrasive recovery apparatus 10 economically non-viable and itimpractical for most cutting environments.

SUMMARY OF THE INVENTION

This invention relates to apparatus and methods for recovering abrasivefrom an abrasive-laden fluid for use with abrasive jet cutting systems.In one aspect, an apparatus in accordance with the invention includes anabrasive-laden fluid handling device coupled to a catcher tank of anabrasive jet cutting system, a pre-classifier fluidly coupled to theabrasive-laden fluid handling device, a hydro-classifier fluidly coupledto the pre-classifier, a fine-particle separation tank fluidly coupledto a clarified-fluid flow outlet of the hydro-classifier, a wet abrasivereceptacle positioned to receive a wet recovered abrasive dischargedfrom the hydro-classifier, a de-watering device engageable with the wetrecovered abrasive in wet abrasive receptacle, and a dryer unit.

In operation, the abrasive-laden fluid handling device provides anabrasive-laden fluid from the catcher tank without requiring mechanicalagitators. The pre-classifier separates the abrasive-laden fluid into ahigh concentration abrasive flow that enters the hydro-classifier, and alow concentration abrasive flow that is shunted back to the catchertank, advantageously allowing a smaller, more economical and practicalhydro-classifier to be used. Further, the de-watering device removes aresidual, interstitial fluid content from the wet recovered abrasive,thereby reducing the energy costs associated with drying the recoveredabrasive.

In a further aspect, the abrasive-laden fluid handling device includesabrasive-laden fluid conduit having a first end in fluid communicationwith the catcher tank and an abrasive-laden fluid outlet positionedoutside of the catcher tank. The abrasive-laden fluid handling devicemay include a fluid drive system coupled to the abrasive-laden fluidconduit, the fluid drive system driving and abrasive-laden fluidcontained within the catcher tank through the abrasive-laden fluidconduit. Alternately, the abrasive laden fluid handling device mayinclude a backflush valve that may be actuated to drive theabrasive-laden fluid back into the catcher tank, thereby flushing anabrasive buildup from the intake of the abrasive-laden fluid conduit. Ina further aspect, the fluid drive system includes a pressurized gassource attached to the abrasive-laden fluid conduit.

In another aspect, an abrasive recovery apparatus includes a de-wateringdevice including a housing having a wet abrasive intake and a de-wateredabrasive outlet spaced apart from the wet abrasive intake, the housingincluding an eductor port situated along an abrasive travel pathextending between the wet abrasive intake and the de-watered abrasiveoutlet, an eductor inlet coupled to the eductor port and coupleable to asource of eduction air, and a transport device that transports the wetrecovered abrasive along the abrasive travel path. In yet anotheraspect, the housing comprises a cylindrical housing and the transportdevice comprises an auger rotatably disposed within the cylindricalhousing. In a further aspect, the apparatus includes an airflow controlvalve fluidly coupled to the eductor port. The airflow control valve maybe positionable in a first position to draw an entrained airflow fromwithin the housing through the eductor port, and a second position tobackflow the eduction air through the eductor port into the housing.

In yet another aspect, a vacuum transport device includes a driedabrasive receptacle, a vacuum pickup having a first end coupleable to asource of vacuum and a second end at least partially disposed within thedried abrasive receptacle and engageable with a volume of dried abrasivetherein, and a standoff housing at least partially disposed about thevacuum pickup and at least partially engageable into the volume of driedabrasive, the standoff housing being positioned relative to the vacuumpickup to maintain a standoff distance between the vacuum pickup and arepose surface of the dried abrasive. The standoff housing maintains thestandoff distance between the vacuum pickup and the repose surface toprevent clogging and ensure operation of the vacuum transport device.

In still another aspect, an abrasive recovery apparatus includes apre-classifier having an abrasive-laden fluid inlet fluidly coupled toan abrasive-laden fluid flow, the pre-classifier separating theabrasive-laden fluid flow into a low-concentration abrasive flow and ahigh-concentration abrasive flow, and having a low-concentration flowoutlet and a high-concentration flow outlet. The pre-classifier mayinclude a turning plate that centrifugally separates thelow-concentration flow from the high-concentration flow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an abrasive recovery apparatus for anabrasive jet cutting system in accordance with the prior art.

FIG. 2 is an isometric view of an abrasive recovery apparatus for anabrasive jet cutting system in accordance with an embodiment of thepresent invention.

FIG. 3 is a schematic view of the abrasive recovery apparatus of FIG. 2.

FIG. 4 is a partially-sectional isometric view of an embodiment of anabrasive-laden fluid collection device of the abrasive recoveryapparatus of FIG. 2.

FIG. 5 is a partially-sectional isometric view of embodiment of ahydro-classifier of the abrasive recovery apparatus of FIG. 2.

FIG. 6 is a partially-sectional isometric view of an embodiment of afine-particle separation tank of the abrasive recovery apparatus of FIG.2.

FIG. 7 is a partially-sectioned isometric view of an embodiment of ade-watering device of the abrasive recovery apparatus of FIG. 2.

FIG. 8 is an enlarged partial cross-sectional view of the air eductiondevice of FIG. 7.

FIG. 9 is an enlarged partial cross-sectional view of the air eductiondevice of FIG. 7.

FIG. 10 is an isometric view of a dryer unit of the abrasive recoveryapparatus of FIG. 2.

FIG. 11 is a partially-sectional isometric view of an embodiment of avacuum transport device of the abrasive recovery apparatus of FIG. 2.

FIG. 12 is a flowchart representation of an embodiment of a process foroperating the abrasive recovery apparatus of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure is directed toward apparatus and methods forrecovering abrasive from an abrasive-laden fluid for use with abrasivejet cutting systems. Specific details of certain embodiments of theinvention are set forth in the following description, and in FIGS. 2-11,to provide a thorough understanding of such embodiments. A person ofordinary skill in the art, however, will understand that the presentinvention may have additional embodiments, and that the invention may bepracticed without several of the details described in the followingdescription.

FIG. 2 is an isometric view of an abrasive recovery apparatus 100 foruse with an abrasive jet cutting system in accordance with the presentinvention. FIG. 3 is a schematic view of the abrasive recovery apparatus100 of FIG. 2 in operation with a catcher tank 16 and cutting head 12 ofan abrasive jet cutting system. In this embodiment, the abrasiverecovery apparatus 100 includes an abrasive-laden fluid handler 210 thatcontinuously removes abrasive-laden fluids from the catcher tank 16without using mechanical agitators to suspend the abrasive particles inthe waste fluid. The abrasive recovery apparatus 100 also includes apre-classifier 120 that improves the quality and limits the amount ofabrasive-laden flow entering a hydro-classifier 130. Finally, theapparatus 100 includes a de-watering device 170 that removes fluid froma wet recovered abrasive prior to entering a dryer, improving the dryingprocess and the economic feasibility of the system.

FIG. 4 is a cross-sectional side elevational view of an embodiment ofthe abrasive-laden fluid handler 210 of FIG. 2. The abrasive-laden fluidhandler 210 is fully shown and described in co-pending U.S. patentapplication Ser. No. 09/069,223, incorporated herein by reference.

Referring to FIGS. 2-4, the catcher tank 16 includes a bottom panel 250,first and second side-walls 251 a and 251 b projecting upward fromopposing sides of the bottom panel 250, and first and second end-walls251 c and 251 d projecting upward from opposing ends of the bottom panel250. The first and second side-walls 251 a and 251 b are attached to thefirst and second end-walls 251 c and 251 d to form a large cavity. Thecatcher tank 16 also includes a central divider 252 (see FIG. 2)extending longitudinally within the tank 16, and a plurality of crossingdividers 254 extending transverse to the central divider 252. Thedividers 252 and 254 define a plurality of compartments 256 (identifiedby reference numbers 256 a-256 c) in the catcher tank 16. Onecommercially-available catcher tank 16 suitable for this purpose is thecatcher tank of the Bengal 4×4 abrasive-jet cutting system availablefrom Flow International Corp. of Kent, Wash.

The compartments 256 receive the abrasive-laden fluid 14 from thecutting bead 12 as the cutting head 12 is traversed along a cutting pathP. Additionally, each compartment 256 is configured to control theabrasive-laden fluid 122 within the tank 16. For example, when theabrasive jet 14 is aligned with compartment 256 b, the dividers 252 and254 defining this compartment control the fluid flow such that theabrasive jet 14 alone suspends a significant portion of the abrasiveparticles in the abrasive-laden fluid 122. As such, by dividing the tank16 into smaller compartments 256, the abrasive jet 14 maintains at leasta substantial portion of the abrasive particles in suspension in theabrasive-laden fluid 122 within a particular compartment aligned withthe abrasive jet 14 without additional mechanical agitation. Typically,each compartment is approximately between 1′×1′ and 4′×8′, and morepreferably about 2′×4′. As explained in more detail below, theabrasive-laden fluid handler 210 continuously removes abrasive-ladenfluid 122 and abrasive particles from the compartments 256.

As shown in FIG. 4, the abrasive-laden fluid handler 210 includes anumber of conduit sections 260 (identified by reference numbers 260 aand 260 b). The conduit sections 260 are configured to transportabrasive-laden fluid 122 from the compartments 256 a, 256 b and 256 c.The conduit sections 260 include at least a first conduit section 260 ahaving a first end 262 positioned in the lower portion of compartment256 b and a second end 264 positioned in compartment 256 a. The firstconduit section 260 a also has a first intake opening 266 proximate tothe bottom panel 250, a second intake opening 268 located to receive afluid flow from a conduit section from the adjacent upstream compartment256 c, and a vent 267 toward the second end 264. The second intakeopening 268, for example, can be a funnel. The conduit sections 260 canalso include a second conduit section 260 b similar to the first conduitsection 260 a, and thus like reference numbers refer to like components.The second conduit section 260 b has a first end 262 positioned in thelower portion of compartment 256 a and a second end 264 coupled to atrough 117. The second intake opening 268 of the second conduit section260 b is located to receive a first fluid flow F₁ from the second end264 of the first conduit section 260 a in a so-called “cascade”arrangement. Accordingly, the first and second conduit sections 260 aand 260 b define a conduit that transports the abrasive-laden fluid 122from the compartments 256 a and 256 b to the trough 117.

To generate fluid flows through the conduit sections 260, a fluid drivesystem 270 is preferably coupled to the conduit sections 260 to drivethe abrasive-laden fluid 122 through the conduit sections 260. In thisparticular embodiment, the fluid drive system 270 includes a fluiddriver 271, a primary line 272 coupled to the fluid driver 271, and aplurality of branch feed lines 274 coupled to the primary line 272. Thefluid driver 271 can be a pressurized gas source, such as an aircompressor. The primary line 272 generally passes through the dividers252 and 254 to supply pressurized gas to all of the compartments 256.The branch feed lines 274 are attached to the conduit sections 260 belowthe fluid level of the abrasive-laden fluid 122 in the compartments 256.

In operation, the pressurized gas source 271 injects a compressed gas278, such as air, into the conduit sections 260. The compressed gas 278is metered into the bottom of each conduit section 270. The gas 278accordingly rises through the vertical portions of the conduit sections260, creating a pumping action that draws abrasive-laden fluid 122through the conduit sections 260. The gas 278 passes through the vents267, while the fluid 122 continues to flow through the conduit sections260. The second conduit section 260 b includes a backflush valve 113which may be used to selectively control the flow of the abrasive-ladenfluid 122 out of the catcher tank 16. The fluid drive mechanism 270,therefore, generates the first fluid flow F₁ through the first conduitsection 260 a and a second fluid flow F₂ through the second conduitsection 260 b and into the trough 117. Typically, each conduit section260 consumes approximately 3 to 5 SCFM and generates approximately 10GPM of abrasive-laden fluid flow through the conduit section 260.

The abrasive-laden fluid handler 210 removes abrasive-laden fluid 122from at least one of the compartments 256 as the abrasive jet 14 movesalong the cutting path P. As the abrasive jet 14 passes over thecompartment 256 b, the abrasive jet 14 agitates the abrasive-laden fluid122 to suspend a significant portion of abrasive particles within thecompartment 256 b without additional mechanical agitation. Thecompartment 256 b is properly sized to permit the abrasive jet 14 toadequately suspend abrasive particles (and fines) in the abrasive-ladenfluid 122 without additional mechanical agitation because the dividers252 and 254 concentrate the turbulence generated by the abrasive jet 14and contain the abrasive particles within the relatively small volume ofcompartment 256 b. The fluid flow F₁ through the first conduit section260 a accordingly draws a portion of the abrasive-laden fluid 122 andthe suspended abrasive particles through the first conduit section 260a. The first fluid flow F₁ exits from the first conduit section 260 a,and the second fluid flow F₂ in the second conduit section 260 a drawsthe first fluid flow F₁ into the second intake opening 268 of the secondconduit section 260 b. The abrasive-laden fluid 122 from compartment 256b is thus transported to the trough 117 through the first and secondconduit sections 260 a and 260 b.

Occasionally, a buildup of abrasive will develop in the catcher tank 16around the intake openings 266 of the conduit sections 260, obstructingthe intake openings 266 and hampering the flow of abrasive-laden fluidinto the conduit sections 260. If enough abrasive buildup occurs, theair bubbles from the fluid drive system 270 will not be able to unplugthe intake openings 266. To remedy this problem, the backflush valve 113(shown in FIG. 4 as a “pinch” valve) may be periodically closed to forceair through the conduit sections 260 and out the intake openings 266,flushing out any buildup of abrasive in the intake region and preventingclogging. The backflushing operation may be automatically controlled bycoupling the backflush valve 113 to a control system and a timer.

The abrasive-laden fluid handler 210 advantageously removes the abrasivefrom the catcher tank 16 without the need for periodic shoveling of thecatcher tank 16. In this way, the costs associated with thelabor-intensive task of removing the abrasive from the tank and thedowntime of the abrasive-jet cutting system are avoided. Anotheradvantage is that the abrasive-laden fluid handler 210 provides acontinuous flow of abrasive-laden fluid to the remaining components ofthe abrasive recovery apparatus 100.

As best shown in FIG. 2, the abrasive-laden fluid 122 flows through thetrough 117 and enters the pre-classifier 120. The pre-classifier 120includes a turning plate 121 that causes the flow of abrasive-ladenfluid 122 to be turned. In the embodiment shown in FIG. 2, the turningplate is positioned at an approximately 45 degree angle to the initialflow direction of the abrasive-laden fluid 122. The pre-classifier 120also includes a low-concentration abrasive flow outlet 126 and ahigh-concentration abrasive outlet 128.

In operation, the abrasive-laden flow 122 enters the pre-classifier 120and is turned by the turning plate 121, subjecting the abrasive-ladenflow 122 to a centrifugal force. As the abrasive-laden flow 122 turnsaround the end of the turning plate 121, it is accelerated, therebyusing the centrifugal force to separate the abrasive-laden flow 122 intoa low-concentration abrasive flow 123 and a high-concentration abrasiveflow 124. The high-concentration abrasive flow 124 flows out of thehigh-concentration abrasive flow outlet 128 and into a hydro-classifier130, as described more fully below. The low-concentration abrasive flow123 exits from the pre-classifier 120 through the low-concentrationabrasive flow outlet 126 and back into the catcher tank 16.

FIG. 5 is a partially-sectional isometric view of an embodiment of thehydro-classifier 130 of the abrasive recovery apparatus 100 of FIG. 2.The hydro-classifier 130 includes an open top 132 through which thehigh-concentration abrasive fluid 124 enters an upper portion 134 of thehydro-classifier 130. A teeter fluid inlet 138 is disposed within amiddle portion 142 of the hydro-classifier 130 and is coupled to asource of teeter (or “clarified”) fluid 136. A manifold 140 distributesthe teeter fluid 136 into the middle portion 142 of the hydro-classifier130. The teeter fluid 136 rises upwardly through the middle portion 142and mixes with the high-concentration abrasive fluid 124 flowingdownwardly from the upper portion 134.

The mixing of the teeter fluid 136 with the high-concentration abrasivefluid 124 separates a recovered abrasive 144 from a fine particle flow147. The fine-particle flow 147 exits from the upper portion of 134 ofthe hydro-classifier 130 via a fine-particle flow outlet 149. As shownin FIG. 5, the recovered abrasive 144 collects in a lower portion 146 ofthe hydro-classifier 130. The lower portion 146 includes a recoveredabrasive outlet 148. A wet abrasive control valve 150 is coupled lo tothe recovered abrasive outlet 148 and is adjustably positionable betweenan open and a closed position. The wet abrasive control valve 150 may beany suitable type, including, for example, a pinch valve.

A pressure transducer 152 is disposed within the middle portion 142 ofthe hydro-classifier 130. The pressure transducer 152 senses a fluidpressure within the hydro-classifier 130. Based on the pressure measuredby the pressure transducer 152, the level of recovered abrasive 144 inthe lower portion 146 may be determined. Based on a measured pressuresignal from the pressure transducer 152, the wet abrasive control valve150 may be opened to release the recovered abrasive 144 from thehydro-classifier 130. Commercially-available hydro-classifiers suitablefor this purpose include, for example, those available from Carpco, Inc.of Jacksonville, Fla.

The pre-classifier 120 advantageously improves the abrasiveconcentration of the fluid entering the hydro-classifier 130. Becausethe low-concentration abrasive flow 123 is separated from thehigh-concentration abrasive flow 124 by the centrifugal force and isre-directed back into the catcher tank 16, the volume of fluid enteringthe hydro-classifier 130 is reduced, and the concentration of abrasivewithin the fluid entering the hydro-classifier 130 is increased. Becausethe size and efficiency of the hydro-classifier 130 is driven by theconcentration of the abrasive-containing fluid entering thehydro-classifier 130, the pre-classifier 120 advantageously permits asmaller, more economically feasible hydro-classifier 130 to be used.Thus, the pre-classifier 120 improves the economic feasibility of theabrasive recovery apparatus 100 and enables the apparatus to be employedmore practically in a wide variety of environments.

Similarly, the abrasive-laden fluid handler 210 advantageously improvesthe abrasive concentration of the fluid entering the hydro-classifier130. The abrasive-laden fluid handier 210 captures the abrasive-ladenfluid 122 that contains a higher concentration of abrasive than theprevious method of simply pumping fluid from the catcher tank 16. Theabrasive-laden fluid handler 210 captures the abrasive-laden fluid 122from the compartments 256 into which the abrasive jet 14 enters thecatcher tank 16, thus enabling a higher concentration abrasive-ladenfluid 122 to be captured and removed from the catcher tank 16. In turn,the higher concentration of abrasive-laden fluid 122 entering thehydro-classifier 130 advantageously permits a smaller, more economicallyfeasible hydro-classifier 130 to be used. Thus, the abrasive-laden fluidhandler 210 improves the economic feasibility and practicality of theabrasive recovery apparatus 100.

FIG. 6 is a partially-sectional isometric view of an embodiment of afine-particle separation device 154 of the abrasive recovery apparatus100 of FIG. 2. The particle separation device 154 includes a settlingtank 156 having a fine-particle flow inlet 158 and a clarified fluidoutlet 160. A plurality of baffles 162 are positioned within thesettling tank 156 between the fine-particle flow inlet 158 and theclarified fluid outlet 160. The baffles 162 slow the speed of the flowentering the settling tank 156 and provide additional surface area forthe accumulation of fine particles. A collection trough 164 is disposedwithin the settling tank 156, traversing the settling tank 156 throughcutouts in the baffles 162 and projecting out of the clarified fluidoutlet 160.

In operation, the fine-particle flow 147 enters the settling tank 156through the fine-particle flow inlet 158. The fine-particle flow 147encounters the baffles 162 which slow the flow and inhibit turbulencewithin the settling tank 156. Into relatively stagnant settling tank156, the fine particle flow 147 separates into a clarified fluid 166 anda fine sediment 168. The fine sediment 168 collects on the baffles 162and eventually drops to the bottom of the settling tank 156 forsubsequent removal and disposal. As the fluid level within a settlingtank 156 increases, the clarified fluid 166 flows over the edges of andinto the collection trough 164, passing through the collection trough164 and out the clarified fluid outlet 160. The clarified fluid 160 maythen be pre-circulated into the catcher tank 16 of the abrasive jetcutting system, or may be disposed of in an environmentally consciousmanner. Suitable fine-particle separation of devices 154 include, forexample, the wet separation gravity separators commercially-availablefrom Outokumpu Technology, Inc. of Jacksonville, Fla.

FIG. 7 is a partially-sectional isometric view of an embodiment of ade-watering device 170 of the abrasive recovery apparatus 100 of FIG. 2.The de-watering device 170 includes a wet abrasive receptacle 172 thatreceives the recovered abrasive 144 from the wet abrasive outlet 148 ofthe hydro-classifier 130, and a wet abrasive transport device 174 havinga cylindrical housing 176 that surrounds an auger 178. The auger 178transports the wet recovered abrasive 144 through the cylindricalhousing 178 past first and second air eduction ports 182, 184 to ade-watered abrasive outlet 186. A variable speed motor 179 is coupled tothe cylindrical housing 178 to drive the auger 178. The recoveredabrasive 144 exits from the de-watered abrasive outlet 186 to a dryerunit 300 (see FIG. 3).

The de-watering device 170 also includes an air eduction system 180having first and second eduction air inlets 183, 185 coupled to thefirst and second eductor ports 182, 184, respectively. First and secondairflow valves 187, 188 are also coupled to the first and second eductorports 182, 184, respectively, to control a flow of air through the firstand second eductor ports 182, 184.

FIG. 8 is an enlarged partial cross-sectional view of the air eductionsystem 180 of FIG. 7. As shown in FIG. 8, the first eductor port 182fluidly communicates with an interior region 190 of the cylindricalhousing 176 via a first eductor aperture 192. Similarly, the secondeductor port 184 fluidly communicates with the interior region 190 via asecond eductor aperture 194. Screens 196 cover the first and secondeductor apertures 192, 194 to prevent the outflow of the wet recoveredabrasive 144 (not shown) out of the interior region 190. The first andsecond eduction air inlets 183, 185 are fluidly coupled to a source ofhigh-pressure air by air supply lines 198.

In a first mode of operation, the first and second airflow valves 187,188 are opened, and a high-pressure air F₁ from the air supply lines 198enters the first and second eduction air inlets 183, 185. As thehigh-pressure air F₁ travels through the first and second air eductorports 182, 184, a flow of entrained air F₂ is pulled by thehigh-pressure air F₁ into the interior region 190 of the cylindricalhousing 176 through the dried-abrasive outlet 186. The flow of entrainedair F₂ is drawn by the high-pressure air F₁ through the wet recoveredabrasive 144 (not shown) in the interior region 190 where it evaporatesand collects moisture from the wet recovered abrasive 144. A wetentrained airflow F₃ is then drawn through the screens 196 and into thefirst and second air eductor ports 182, 184. The wet entrained airflowF₃ mixes with the high-pressure air F₁ to form a wet exhaust flow F₄that is blown out of the first and second airflow valves 187, 188.

Thus, in the first mode of operation shown in FIG. 8, the air eductionsystem 180 advantageously removes a residual, interstitial moisturecontent from the wet recovered abrasive 144. As the auger 178continuously pushes wet recovered abrasive 144 through the interiorregion 190 of the cylindrical housing 176, the air eduction system 180removes residual moisture from the recovered abrasive 144 to produce ade-watered abrasive 144A. By lowering the water content of thede-watered abrasive 144A prior to delivery to the dryer unit 300, theamount of energy needed to dry the de-watered abrasive 144 is reduced.Consequently, the operational costs of the abrasive recovery apparatus100 are reduced, making the abrasive recovery operation moreeconomically feasible.

One may note that several of the features of the air eduction system 180may be varied from the embodiment described above and shown in theaccompanying figures. For example, one of the air eduction ports, aireduction inlets, and airflow control valves may be eliminated, or anynumber of air eduction ports may be added. Alternately, an air eductionsupply port may be added within the cylindrical housing 176 so that theflow of entrained air F₂ enters through a separate air eduction supplyport rather than through the de-watered abrasive outlet 186. The augermay be replaced by an equivalent transport device. Of course, thedimensions and specific design details of the air eduction systemcomponents may also be varied without deviating from the scope andspirit of the invention.

Although the dimensions of the air eduction system 180 may be varied toachieve acceptable results, experiments have shown that theeffectiveness of the air eduction system 180 is effected by the size ofthe auger 178 and inside diameter of the cylindrical housing 176. If thedimensions of the air eduction system 180 are held constant, reducingthe diameter of the auger/cylindrical housing improves the de-wateringeffect of the air eduction system. For example, for an air eductionsystem 180 having first and second air eduction ports 182, 184 eachbeing 0.5 inches in diameter, and a de-watered abrasive outlet 186 thatis 1.0 inches in diameter, and a high-pressure supply of air F₁ ofapproximately 60 psi, a 1 inch diameter auger/cylindrical housing(inside diameter) is preferred over an auger/cylindrical housing oflarger diameter. Regardless of the actual dimensions and operatingconditions, the air eduction system 180 preferably (but not necessarily)provides a de-watered abrasive 144A having approximately 11 percent orless water content by weight.

FIG. 9 is an enlarged partial cross-sectional view of the air eductionsystem 180 of FIG. 7 in a second mode of operation. In this second mode,the first and second airflow valves 187, 188 are closed, causing thehigh-pressure air F₁ to flow back through the first and second aireduction ports 182, 184 and into the interior region 190 of thecylindrical housing 176. The backflow F₄ of air passes through thescreens 196 covering the first and second eductor apertures 192, 194,dislodging and clearing any of the wet recovered abrasive 144 from thescreens 196. The backflow F₄ of air then passes through the de-wateredabrasive 144A (not shown), and ejects a volume of the de-wateredabrasive 144A out of the interior region 190 through the de-wateredabrasive outlet 186. Thus, in the second mode of operation shown in FIG.9, the air eduction system 180 blows a mixture of air and de-wateredabrasive F₅ out the de-watered abrasive outlet 186.

In the second mode of operation, the air eduction system 180advantageously provides the backflow F₄ of air through the screens 196to keep the screens unblocked. The backflow F₄ ensures that the screensremain unblocked so that in the first mode of operation the wetentrained airflow F₃ passes readily through the screens 196 to maximizethe drying of the recovered abrasive 144. By alternating between thefirst and second modes of operation, the wet recovered abrasive 144 maybe de-watered and then the airflow through the air eduction apertures192, 194 reversed to unblock the screens 196. For an air eduction system180 having the dimensions and operating parameters described above,desirable results have been achieved by operating the system forapproximately one-minute in the first mode of operation to de-water therecovered abrasive 144, and then switching to the second mode ofoperation for approximately one second to unblock the screens 196.

Another advantage is that in the second mode of operation, the aireduction system 180 blows the air and dried abrasive mixture F₅ out ofthe de-watered abrasive outlet 186 to help break up clumps of de-wateredabrasive 144A. It is known that large clumps of abrasive are moredifficult to dry than smaller clumps or individual abrasive particles.When the air eduction system 180 is operated in the second mode ofoperation shown on FIG. 9, the pulse of air and dried abrasive mixtureF₅ has the desirable effect of helping to break up clumps of thede-watered abrasive 144A exiting from the de-watered abrasive outlet186. Thus, the de-watered abrasive 144A may be more efficiently dried bythe dryer unit 300 as described more fully below.

It is understood that in an alternate embodiment, the air eductionsystem 180 may be modified to operate using a vacuum system. Forexample, in the first mode of operation, the first and second aireductor ports 182, 184 may be coupled to the vacuum system so that theflow of entrained air F₂ is drawn into and through the interior region190, and the wet entrained airflow F₃ is drawn through the screens 196and out through the first and second airflow valves 187, 188. In thisembodiment, the high-pressure eduction air F₁ from the air supply lines198 would be unnecessary in the first mode of operation. In the secondmode of operation, however, the first and second airflow valves 187, 188would be closed to the vacuum system, and the high-pressure air F₁ fromthe air supply lines 198 would be used to generate the backflow F₄ ofair through the screens 196. Furthermore, because the eduction air actssimilar to a source of vacuum by drawing the flow of entrained air F₂into and through the interior region 190, and the flow of wet entrainedair F₃ out through the screens 196, the use of the term “eductor”throughout this discussion may in most cases be interchanged with theterm “vacuum.”

In another alternate embodiment, a de-watering airflow may simply beblown through the wet recovered abrasive 144. For example, thede-watered abrasive outlet 186 may open into a pressurizeable chamber700 (shown in dashed lines in FIG. 8) coupled to a source of pressurizedair 710 (e.g. a pump). With the pressurizeable chamber 700 pressurized,a de-watering airflow may flow from the pressurizeable chamber 700through the interior region 190 and the wet recovered abrasive 144 andout of the housing 176. The de-watering airflow may exit the housing 176through, for example, the ports 182, 184, or may simply blow thede-watering airflow out of the open end of the housing at which theauger 178 picks up the wet recovered abrasive 144 from the wet abrasivereceptacle 172.

FIG. 10 is an isometric view of the dryer unit 300 of the abrasiverecovery apparatus 100 of FIG. 2. The dryer unit 300 includes acontainment tank 302 having a de-watered abrasive inlet 304 and a driedabrasive outlet 306. A horizontal floor partition 320 separates theinterior of the containment tank 302 into an upper drying chamber 310and a lower heater chamber 330. The floor partition 320 is porous andpermits the flow of air from the lower heater chamber 330 to the upperdrying chamber 310. A plurality of path control walls 308 span thedrying chamber 310 and divide the drying chamber 310 into a plurality ofdrying sections 309 (designated as 309A, 309B, and 309C in FIG. 10).Each path control wall 308 includes an upper edge 312 having a notch 314formed therein. A layer of drying abrasive 315 partially fills thedrying chamber 310. The layer of drying abrasive 315 may include apriming layer of abrasive, or may be formed by the de-watered abrasive144A entering the de-water abrasive inlet 304.

A plurality of heater elements 332 are positioned within the lowerheater chamber 330. A heating air inlet 334 is disposed within a lowerportion of de-containment tank 302 to allow a flow of heating air 336 toenter the lower heater chamber 330. A blower 338 is coupled to theheating air inlet 334 by a blower duct 340. An exhaust port 316 projectsfrom an upper surface 318 of the containment tank 302 to vent exhaustgases from the drying chamber 310. A temperature sensor 317 ispositioned within the exhaust port 316 to monitor the temperature of anexhaust flow F₆ from the drying chamber 310.

In operation, the de-watered abrasive 144A enters the drying chamber 310through the de-watered abrasive inlet 304 and mixes with the layer ofdrying abrasive 315. The blower 338 forces the flow of heating air 336into the lower heater chamber 330 and over the heater elements 332. Theheating airflow 336 is heated by the heater elements 332 and passesthrough the porous floor partition 320. The heating airflow 336 thenpasses through the layer of drying abrasive 315 in the drying chamber310. During this operation, the layer of drying abrasive 315 becomes ahot, fluidized layer and is heavily agitated by the heating airflow 336.

As damp de-watered abrasive 144A is introduced into the drying chamber310, the level of the layer of abrasive 315 in the first drying section309A continues to rise to the top of the first path control wall 308.The larger and damper clumps of de-watered abrasive 144A sink to thebottom of the layer of abrasive 315 and are reduced in size. As thede-watered abrasive 144A dries, it rises to the surface of the layer ofabrasive 315 and works its way over the notches 314 of the path controlwalls 308 into the next drying section 309. In this embodiment, thenotches 314 in the path control walls 308 are positioned at alternatingsides of the containment tank 302 in a “labyrinth” arrangement toincrease the travel path of the de-watered abrasive 144A through thedrying chamber 310.

The heating airflow 336 passes through the layer of abrasive 315,separating and removing the residual, interstitial moisture containedwithin the de-watered abrasive 144A. The heating airflow 336 andresidual moisture vapor form the wet exhaust flow F₆ that exits from thedrying chamber 310 through the exhaust port 316. The de-watered abrasive144A is dried to form a dried abrasive 144B that exits from the dryingchamber 310 via the dried abrasive outlet 306.

FIG. 11 is a partially sectional isometric view of an embodiment of avacuum transport system 400 of the abrasive recovery apparatus 100 ofFIG. 2. The vacuum transport system 400 includes a dried abrasivereceptacle 402 that receives and contains the dried abrasive 144B fromthe dried abrasive outlet 306 of the dryer unit 300. A vacuum pickup 404is partially inserted into the dried abrasive 144B within the driedabrasive receptacle 402. A standoff housing 406 surrounds the vacuumpickup 404 and is also partially inserted into the dried abrasive 144Bwithin the dried abrasive receptacle 402. A vacuum line 408 couples thevacuum pickup 404 to a vacuum pump 410, and the vacuum pump 410 iscoupled to a vacuum exhaust outlet 411. An abrasive catch vessel 412 iscoupled with the vacuum line 408 between the vacuum pickup 404 and thevacuum pump 410. The abrasive catch vessel 412 is equipped with anoutlet valve 414 that controllably releases the dried abrasive 144B intoa storage vessel 416.

The vacuum pump 410 pulls a vacuum in the vacuum line 408 and vacuumpickup 404, drawing a flow of transport air F₇ and dried abrasive 144Bout of the dried abrasive receptacle 402 and into the vacuum line 408.As the vacuum pickup 404 withdraws the dried abrasive 144B from thedried abrasive receptacle 402, an approximately conical depression 407is formed at the lower end of the standoff housing 406. The flow oftransport air F₇ and dried abrasive 144B is drawn through the vacuumline 408 and is deposited into the abrasive catch vessel 412. The outletvalve 414 periodically opens to release the dried abrasive 144B into thestorage vessel 416. The flow transport air F₇ passes through the vacuumpump 410 and exits through the vacuum exhaust outlet 411.

The vacuum transport system 400 advantageously maintains the performanceof the vacuum pickup 404 for removing the dried abrasive 144B despitevariations in the level of the dried abrasive 144B within the driedabrasive receptacle 402. The performance of the vacuum pickup 404 isachieved when the vacuum pickup 404 is maintained at a close standoffdistance from the surface of the dried abrasive 144B. If the vacuumpickup 404 is too far from the surface of the dried abrasive 144B, knowof dry abrasive 144B will be transported. If the vacuum pickup 404 istoo close to the surface of the dried abrasive 144B, the vacuum pickup404 will clog. To overcome the problem presented by variations in thelevel of the dried abrasive 144B, the standoff housing 406 is positionedproximate the vacuum pickup 404 to maintain the desired close standoffdistance between the surface of the dried abrasive 144B and the vacuumpickup 404. The angle of the conical depression 407 is controlled by theangle of repose of the dried abrasive 144B as the dried abrasive 144Btumbles into the conical depression 407. By adjusting the position ofthe standoff housing 406 relative to the vacuum pickup 404, the desiredclose standoff distance is maintained.

FIG. 12 is a flowchart representation of an embodiment of a process 500for operating the abrasive recovery apparatus 100 of FIG. 2. In thisembodiment, the operating process 500 includes starting the main pump ofthe abrasive jet cutting system 502. Next, the fluid drive system of theabrasive-laden fluid handling system is started 504. The flow of teeterfluid to the hydro-classifier is also started 506.

After these systems are started, the pressure in the hydro-classifier ismonitored, and a determination is made whether the pressure in thehydro-classifier has reached a certain percentage (X %) of apredetermined threshold pressure 508. The predetermined thresholdpressure is the pressure at which the hydro-classifier is considered tobe “full” of wet recovered abrasive and the wet recovered abrasiveoutlet of the hydro-classifier needs to be opened.

If the pressure in the hydro-classifier has not reached the certainpercentage (X %) of the predetermined threshold pressure 508, then adetermination is made whether the main pump of the abrasive-jet cuttingsystem is still on 510. If the main pump is not running, then the teeterfluid flow is shut off, and the abrasive-laden fluid handling system isalso shut off 512. The teeter fluid flow and the abrasive laden fluidhandling system may be shut off simultaneously or successively.Operation of the abrasive recovery apparatus is then complete 514. Ifthe main pump is not shut off and is still running 510, however, theoffering process continues to monitor the pressure in thehydro-classifier 508.

When the pressure in the hydro-classifier has reached the certainpercentage (X %) of the predetermined threshold pressure 508, then adetermination is made whether the dryer unit has been started 516. Ifnot, the dryer unit is started by turning on the heater elements and theblower 518. The heater elements may be adjustably controlled until atemperature of the exhaust flow F₆ the dryer unit reaches a desiredexhaust flow temperature.

Next, it is determined whether the main pump of the abrasive jet cuttingsystem is still on 520. If the main pump is still on, a determination ismade whether the pressure in the hydro-classifier has reached 100% ofthe predetermined threshold pressure 522. If the pressure has notreached the predetermined threshold pressure, the operating processreturns to the monitoring of the pressure in hydro-classifier 508.

If the main pump is not still on 520, or if the main pump is still on520 and the pressure in the hydro-classifier has reached 100% of thepredetermined threshold pressure 522, the wet recovered abrasive isdumped from the hydro-classifier via the wet abrasive outlet into thewet abrasive receptacle 524. After the wet recovered abrasive is dumped,the de-watering device is operated until the wet recovered abrasive hasbeen de-watered and transported into the dryer unit 526. Next, theexhaust temperature of the dryer unit is monitored 528.

Based on the exhaust temperature of the dryer unit, the determination ismade whether evaporation in the dryer unit is complete 530. This may beaccomplished in various ways, including by monitoring the time historyof the exhaust temperature. For example, the initial exhaust temperaturemay be the desirable exhaust temperature prior to entry of thede-watered abrasive into the dryer unit. As the de-watered abrasiveenters dryer unit, the exhaust temperature may drop due to theevaporation of residual fluid in the de-watered abrasive. After a periodwithin the dryer unit, the exhaust temperature may then rise again tothe desirable exhaust temperature, indicating that the residual,interstitial fluid within the de-watered abrasive has been removed, andthe drying of the de-watered abrasive is complete.

If the evaporation in the dryer unit is not complete 530, the exhausttemperature of the dryer unit continues to be monitor 528. After theevaporation in the dryer unit is complete 530, the dryer unit shuts off532. The determination is then made whether the main pump of theabrasive jet cutting system is still on 534. If it is, the operatingprocess returns to the monitoring of the pressure in thehydro-classifier 508, and a process is repeated. If, however, the mainpump is not still on 534, the teeter fluid flow to shut off and theabrasive-laden fluid handling system to shut off 512, and the operatingprocess is terminated 514.

Generally, the predetermined threshold pressure for considering thehydro-classifier to be full of wet recovered abrasive, the certainpressure (X %) at which the dryer unit is turned on, and the desiredexhaust temperature of the dryer unit are all system specificcharacteristics. The actual values of these parameters that may be usedin the operating process 500 may depend on several system specificvariables, including, for example, the dimensions of the components(e.g. the hydro-classifier) of the abrasive recovery apparatus 100, theoperating conditions of the abrasive jet cutting system, the type ofabrasive and cutting fluid being used, the power and efficiency of thedryer unit, and other variables.

Several aspects of the operating process 500 advantageously save energyand reduce operating costs compared with the prior art process. Forexample, because the dryer unit is not started until the pressure in thehydro-classifier has achieved the certain percentage (X %) of thepredetermined threshold pressure, energy savings are realized. Also, bymonitoring the exhaust temperature from the dryer unit and shutting offthe dryer unit when evaporation is complete, additional energy savingsare achieved. In addition, the de-watering device is operatedselectively rather than continuously, and is used only when necessary tode-water and transport the wet recovered abrasive from the wet recoveredabrasive receptacle to the dryer unit. Finally, the operating processcontains several steps to determine whether the main pump of theabrasive jet cutting system is still on, and shuts the abrasive recoveryapparatus down automatically when the abrasive-jet cutting system isshut down.

Improved apparatus and methods for recovering abrasive from anabrasive-laden fluid for use with abrasive jet cutting systems have beenshown and described. From the foregoing, it will be appreciated thatalthough embodiments of the invention have been described herein forpurposes of illustration, various modifications may be made withoutdeviating from the spirit of the invention. Thus, the present inventionis not limited to the embodiments described herein, but rather isdefined by the claims which follow.

What is claimed is:
 1. An abrasive recovery apparatus for use with anabrasive-jet cutting system, comprising: a de-watering device includinga housing having a wet abrasive intake and a de-watered abrasive outletspaced apart from the wet abrasive intake, the housing including avacuum port situated along an abrasive travel path extending between thewet abrasive intake and the de-watered abrasive outlet; a vacuum inletcoupled to the vacuum port and coupleable to a source of vacuum; and atransport device that transports the wet recovered abrasive along theabrasive travel path.
 2. The abrasive recovery apparatus according toclaim 1 wherein the housing comprises a cylindrical housing and thetransport device comprises an auger rotatably disposed within thecylindrical housing.
 3. The abrasive recovery apparatus according toclaim 1, further comprising a screen positioned over the vacuum port. 4.The abrasive recovery apparatus according to claim 1, further comprisingan airflow control valve fluidly coupled to the vacuum port.
 5. Theabrasive recovery apparatus according to claim 4 wherein the airflowcontrol valve is positionable in a first position to draw an entrainedairflow from within the housing through the vacuum port, and a secondposition to backflow a pressurized air through the vacuum port into thehousing.
 6. The abrasive recovery apparatus according to claim 1 whereinthe vacuum port comprises a first vacuum port and the vacuum inletcomprises a first vacuum inlet, further comprising a second vacuum portdisposed within the housing along the abrasive travel path, and a secondvacuum inlet coupled to the second vacuum port and coupled to a sourceof vacuum air.
 7. The abrasive recovery apparatus according to claim 1wherein the source of vacuum includes a flow of eduction air into thevacuum inlet.
 8. The abrasive recovery apparatus according to claim 7wherein the eduction air entering the vacuum inlet draws an entrainedairflow into the de-watered abrasive outlet.
 9. The abrasive recoveryapparatus according to claim 1 wherein the vacuum air draws theentrained airflow at least partially through the housing and theabrasive travel path, and through the vacuum port.
 10. The abrasiverecovery apparatus according to claim 1, further comprising ahydro-classifier fluidly coupled to an abrasive-laden fluid flow fromthe abrasive jet cutting system, the hydro-classifier having a teeterfluid inlet coupleable to a fluid source providing a teeter fluid flowthat mixes with the abrasive-laden fluid flow to form a fine-particleflow and a wet recovered abrasive, the hydro-classifier having afine-particle flow outlet and a wet abrasive outlet operatively coupledto the wet abrasive intake of the de-watering device.
 11. The abrasiverecovery apparatus according to claim 1, further comprising a dryer unithaving a de-watered abrasive inlet positioned to receive a de-wateredabrasive from the de-watered abrasive outlet, the dryer unit having aheating element and a dried-abrasive outlet.